The number of prescriptions filled rose 9.7 percent at established stores

Walgreen Co. sales rose 4 percent in April from the same month a year ago, the retailer said Friday, as a huge jump in prescriptions offset lower customer traffic overall.

Walgreens stores saw total sales of $5.98 billion.

The number of prescriptions filled rose 9.7 percent at established stores, or those open at least a year, while customer traffic in those stores fell 5.9 percent. Walgreen Co. attributed its prescription growth to a combination of calendar shifts and the boost from former Express Scripts customers returning to Walgreens locations.

Total sales excluding prescriptions fell 2.9 percent in April, while that metric at established stores fell 4.3 percent.

Customers spent slightly more per transaction, though, as the size of an average purchase rose 1.6 percent at stores open at least 12 months. Sales at locations open at least 12 months are a key measure of retailer health because they exclude the boost from newly opened stores.

Walgreens opened 14 stores during April, including four relocated locations. It closed one store last month.